This invention relates to a double-rotatable universal head for machine tools.
Double-rotatable universal heads for machine tools are known. They receive their motion from a generally horizontal drive shaft and transmit it to the spindle shaft irrespective of the orientation of this latter.
One of such known heads comprises substantially a head carrier rotatably connected to the machine tool slide, and an actual head rotatably connected to the head carrier and having that surfaace in contact therewith inclined at 45.degree. to the drive shaft axis.
The head carrier is provided internally with a motion transmission shaft inclined at 445.degree. to the drive shaft and to the spindle axis.
In order to position the spindle in the required direction, the operator slackens the connection bolts, rotates the head carrier about the slide and rotates the head carrier. Suitable tables define the angles through which the head and head carrier have to be rotated in order to position the spindle in the required direction.
These known heads suffer however form certain drawbacks, and in particular:
a lengthy time period necessary to position the spindle in the required direction because of the bolt and screw connection system between the mutually coupled parts,
a certain operator difficulty in setting the spindle in the required position because of the weight and size of the head and head carrier.
To obviate these drawbacks, automatically positionable universal heads have been proposed in which the head and head carrier are oriented by means of two direct current motors.
However, such heads have other drawbacks, in particular an additional cost and large overall size due to the presence of the two motors and their relative dependent systems. Moreover, the power developed by the spindle cannot exceed a certain value because the head, head carrier and slide are locked together by the action of the motors and rotation mechanisms themselves, with obvious limited efficiency.
A head is also known in which the engagement between the head carrier and slide and between the head and head carrier is obtained by an insertion-fit system, commonly known as "irt" toothing, comprising two annular flanges having their facing surfaces provided with teeth. The head and head carrier are oriented by means of a motor or a pneumatic or hydraulic system, and once they have reached their required position they are locked together by the engagement of the teeth.
The drawbacks of this head consist of high cost due to the rotation system and coupling device, and the noninfinitely variable adjustment which is obviously related to the toothing pitch.